The Radiochemistry Core is broad in scope in its support of the program project grant. Its duties are threefold: 1) a service component whose goal is to provide the synthesis and quality control of CNS agents required for the proposed clinical and preclinical (animal) research studies; 2) maintenance, repair of existing production systems and development new remote chemistry, and quality control hardware; 3) a research component whose goal is the development of new receptor based agents and radiolabeled precursors. These proposed new receptor ligands will broadly reflect the areas of clinical expertise and interest exhibited in the submitted clinical projects in this grant renewal. The service component of the core currently provides 5 radiopharmaceuticals in support of the program project grant: 18FDG (glucose metabolism), 15O- agents including H215O (flow), 15O-O2 (oxygen metabolism) and C15O (blood volume) and 18F-NMSp (dopamine D2 neuroreceptor quantitation). Remote production systems are operational for the continued availability of these agents. The research component will include continued development of fluorinated precursors, i.e. 18F-trifluoroacetate and its reduced derivatives and 18F- fluorobenzyl iodide. We will also develop fluorinated 18F-labeled D1 receptor antagonists (SCH 23390 analogs), based on our 18F-trifluoroacetate chemistry, and synthesis of 18F-labeled central (Type-I/II nonselective and Type-I selective) benzodiazepine analogs. Neither 18F-labeled D1 nor 18F- labeled central benzodiazepine receptor agents are currently available which are suitable for PET investigations of these receptor systems. These agents are being developed to broadly support future receptor based program investigations in schizophrenia, Parkinson's disease, epilepsy, ischemic cerebrovascular disease, depression and Alzheimer's disease.